As to the method which has been conventionally used for mounting an electronic part onto a substrate or the like, a method has been employed wherein the electronic part is temporarily fixed on a substrate to which a solder is previously spotted at a prescribed position, and then, the electronic part is fixed by melting the solder by heating this substrate with an infrared beam, a hot air, or the like (reflow method). With this method, a mounting density of the electronic part on the substrate's surface can be increased.
However, it cannot be said that electronic parts which have been conventionally used have a sufficient heat resistance; especially in the reflow process using an infrared beam for heating, temperature of the part's surface increases locally, thereby causing a problem including generation of deformation thereof; and therefore, a resin composition and an electronic part having further higher heat resistance (especially heat distortion resistance) have been desired.
An LED element, one of semiconductor light-emitting devices, is so small in size with a long life, and is also excellent in saving of an electric power, so that this is widely used as a light source of a display lamp and so forth. Moreover, in recent years, because an LED element having a further higher luminance has been manufactured with a comparatively cheap cost, use of the LED element is being studied as a light source to replace a fluorescent lamp and an incandescent light bulb. When applying to the light source like this, in order to obtain a large luminance, widely employed is a method wherein a surface-mounting LED package is used, namely, a method wherein an LED element is disposed on a substrate which is made of a metal including aluminum and copper (lead frame), and also a reflector (reflecting body) which reflects a light to a prescribed direction is arranged around each LED element.
However, in the illuminating LED device using the method like this, because the LED element generates a heat when emitting a light, the reflector is deteriorated due to a temperature rise during the time of light emission of the LED element thereby causing a decrease in the reflectance thereof. As a result, the luminance thereof decreases, resulting in shortening of the life or the like of the LED element. Therefore, the reflector is required to have a heat resistance.
In order to satisfy the requirement in the heat resistance, in Patent Literature 1, a resin composition comprising (A) a fluorinated resin having a carbon-hydrogen bond and (B) titanium oxide is proposed. In Patent Literature 2, a resin composition for a reflector which includes polymethylpentene, white pigment, and spherical fused silica particle and/or modified cross-section glass fiber is proposed.